Boost spike?

[555 Markus]

OK, not going to pretend I belong in the technical section and know anything about this, but hope one of you guys does!

Just wondering if I experienced my first boost spike since Bob Rawle remapped my MY02 sti last May? Accelarating hard in fifth and sixth boost will normally peak and hold at 1.5bar. Last night while doing this I hit a new peak!

http://images.fotopic.net/y4fgco.jpg

It happened so quickly, but the things I recall are increased volume (whoosh) from the induction kit (recommended and fitted by Bob), and momentary surge forward. Outside air temp was about 2deg C, but I've had no other problems in the cold weather, and haven't been able to replicate the peak since.

Car spec is here : http://www.sussexscoobies.co.uk/forums/showthread.php?t=485

Any ideas? Cheers

Mark

[Scott.T]

It may of been a weather thing as it is ****** cold at the moment. We've still got snow out the front from 2 days ago.

I assume you are now running a 3-port (as bob normally fits these), if so that rules a partial blockage of the restrictor out of the equation.

[555 Markus]

Hi Scott

Thanks for the reply. I thought it might be weather related, but, as I said, I've not had any other instances of this happening.

Still running a 2 port, as Bob deemed it not necessary to change to a 3 port.

Will see if this reoccurs, and if so will most likely contact Bob for advice.

Cheers.

Mark

[Dyney]

Has it been serviced recently? Topped the oil up?

Opened the bonnet? ;)


If it happens again give me a shout and I'll pop round and take a look :)

[555 Markus]

Thanks Iain.

No recent service. Its about 7k into a 10k service interval, and oil level is fine.

Fingers crossed it was just a one off, but will give you a buzz if it reoccurs.

Mark

[Scott.T]

I've found that the 2 port can be very susceptible to temperature.
Also the restrictor size need only vary by a slight amount to change the boost.

Ran mine with a 1.0mm restrictor and a <1.1mm (something like 1.05mm) and it made a 0.2 bar difference in spike.

Hence your pipe may be slightly blocked, or it may of been and is now clear.

The pipe in question is between the turbo outlet and the actuator. It's quite short with a t-piece in it. The restrictor is in the 1/2 nearest the turbo.

[ScoobyDuck]

mines fluttering now in the cold weather and causing it to 'pulse' on WOT coz its very slightly overboosting then dropping then it picks up again. so had to fiddle the duty cycle - but will only hold 1.2 bar steadily now :(

[Nathan L]

Cold Weather = http://members.aol.com/nathlang/defiboost.jpg

And a very big :D

[ScoobyDuck]

ok, ok .. some of us can barely make 1.2bar :cry2: